Noise pollution is as much a problem underwater as it is on land. In response, new Australian-made technology has been designed to help protect marine life.
You may enjoy the peaceful stillness you experience when you swim in the sea, but the ocean is anything but quiet for its underwater residents.
The noise created from commercial shipping and marine industrial development can have strong negative effects on marine species that rely on sound to navigate, hunt, avoid predators and communicate. The stress it causes can disrupt reproduction and migration patterns, resulting in the decline of biodiversity and ecosystem resilience.
Healthy marine species lead to a healthy ocean. The UN estimates the ocean absorbs around 23 per cent of annual carbon dioxide emissions generated by human activity and helps mitigate the impacts of climate change. The ocean has also absorbed more than 90 per cent of the excess heat in the climate system.
Reflecting a growing international consensus that ocean noise must be addressed to meet global biodiversity and climate goals, this week at the UN Oceans Conference leaders from 37 countries launched the High Ambition Coalition for a Quiet Ocean, the first global political coalition dedicated to reducing harmful ocean noise pollution.
While the coalition’s main focus is the reduction of shipping-related noise and impacts, it will also address issues such as incorporating acoustic protection into marine protected areas and supporting science-based international regulations to protect highly sensitive species such as whales.
New program protects marine life
Australia is not part of this coalition, however the stronger global focus on the health of the ocean is still good news for GHD, an Australian-based engineering company that works across five continents.
With underwater noise already a crucial component of environmental impact studies, GHD saw an opportunity to create a user-friendly modelling program designed to mitigate the environmental impacts of projects such as offshore wind farms.
Marco Velasco, GHD’s Senior Consultant in the Air & Noise Service Line, said that existing solutions can be a “black box”, complicated to use and lack flexibility.
“What we aimed to do is develop a program which allowed more flexibility and also allows batch-processing for a large number of scenarios,” Velasco told create. “Each scenario involves multiple gigs of data – where the model domain can be tens of kilometres long and 500 m deep – and we are reducing the dimensions at each step. The end result, called RAT (R Acoustics Toolbox), is a visualisation tool that produces GIS format outputs , which are easier for a regulator or a client to interpret.”
Pri Pandey, GHD Service Line Leader – Air & Noise, explained that compared to airborne acoustics, underwater acoustics is a very computational field.
“Unlike airborne acoustics, which [are] mostly empirical equations baked into commercial software, underwater acoustics is numerical modelling. You’ve got a range-depth grid along bathymetric transects, different sea floor conditions, and complex algorithms that have been developed by the US Navy and others that see standard use.
“We wanted to build something that was super intuitive and basically brought these complex algorithms to the user in a way that allows us to quickly model different scenarios, understand the impact of mitigation, visualise different transects and how noise propagates along those transects visually.”
Developed using R programming language, the scenarios can be manipulated depending on the thresholds for different species, such as whales, dolphins or seals, as well as what the source of the noise will be, such as continuous sounds such as drilling or impulsive noise such as piling.
Unique all-in-one solution
While there are other solutions in the market that compute the data and analyse the results in separate functions, Velasco said the GHD model was unique in that the database, threshold evaluation and visualisation are within the same program.
“It is a tool for propagation modelling. It also incorporates the hearing thresholds for marine mammals and calculates the distances and the zones of influence to those thresholds, all within the one package.”
Pandey said that data such as whale migration routes can be incorporated during the impact assessment phase.
“If we are looking at certain zones, and if we identify that there’ll be whale migration paths through that zone, we can use that information to quantify the duration of the migration versus the duration of the proposed noise generating activities, and what those impacts will be.”
He said GHD will use RAT on upcoming wind farm projects in Australia, and has already successfully deployed it on oil and gas projects in the Middle East, defence projects across Australia, and geophysical surveys in the UK, with positive feedback from those clients.
Looking ahead, GHD plans to continue enhancing the RAT by adding features such as full movement models to simulate how species respond to noise over time.
“We want to make it interactive so we can see in real time how mitigation options reduce impacts,” Velasco said. “It’s a powerful toolbox.”
